[Do viruses participate in the origin of group outbursts of gene mutations occurring in natural Drosophila populations?].

It has been experimentally shown that different viruses apathogenic for Drosophila and unable to reproduce in it, and also highly polymerized DNA isolated from these viruses, act as effective mutagens when injected into the hemolymph of this insect. They induce numerous lethal and visible stable gene mutations. Some of them can be present in Drosophila natural populations.

[Mutation "outbursts" of various genes in natural populations of Drosophila melanogaster].

Mutation outbursts of several sex-linked genes are described. The outbursts occurring in natural populations of Drosophila melanogaster in various periods are shown to result mainly from transpositions of mobile genetic elements.

[The selectivity of the mutagenic action of DNA and other polynucleotides].

A paper summarises the results of author's and his collaborators studies on the mutagenic action of DNA and other natural and synthetic polynucleotides. These results were published with rare exception in Russian and Ukrainian scientific journals. Analogous results obtained by other authors of several countries are also discussed.

[The passive transfer by Drosophila spermatozoa of exogenous DNA molecules or synthetic polynucleotides into fertilizable eggs].

Experiments on mutation induction in Drosophila melanogaster by injections of exogenous DNAs or a synthetic polyribonucleotide solutions into the hemolymph of the male demonstrated that Drosophila spermatozoa were able to transfer passively molecules of these mutagens into fertilized eggs. This induced mutations in both paternal and maternal chromosomes in offspring.

[The role of double-stranded DNA breaks in the mechanism of meiosis].

A review is given of recent publications devoted to the investigation of molecular mechanisms of meiosis. It is stated that double-strand breaks of chromosomal DNA, which can be successfully repaired during meiosis, are also the cause of meiotic conjugation of homologous chromosomes and of their genetic recombination (crossing-over). Arguments are presented that meiosis had historically arisen from the reparation of double-strands breaks of DNA during mitosis.